Abbreviation List: 9,266 Abbreviations and What They Mean

AbbreviationList is a free English dictionary of abbreviations, acronyms and initialisms. It explains 9,266 abbreviations and 14,175 meanings across medicine, government, technology, business, science and everyday writing. When an abbreviation stands for more than one thing, every meaning is listed with its context, a plain-English definition and a real-world example.

Popular abbreviations

Abbreviations by category

Medical Abbreviations

2,747 entries · ACA, ADHD, AIDS, BMI, BMP

Geography & Place Abbreviations

657 entries · AK, AL, Apt, AR, Ave

Government & Political Abbreviations

785 entries · 911, ADA, CCP, CDC, CIA

Units of Measurement Abbreviations

540 entries · APR, Aug, BST, C, CI

Science & Engineering Abbreviations

808 entries · AC, AU, C, DC, DNA

Technology & Computer Abbreviations

1,322 entries · 4G, 4K, 5G, AI, API

Business & Finance Abbreviations

1,475 entries · 1040, 1099, 401(k), APR, APY

Legal Abbreviations

496 entries · IP, NDA, ABA, DA, Esq.

Texting & Internet Slang Abbreviations

606 entries · AFK, BF, BFF, BRB, BTW

Common Abbreviations

540 entries · AD, aka, AM, ASAP, CC

Education & Academic Abbreviations

715 entries · ACT, AP, BA, BS, CPA

Military Abbreviations

782 entries · AWOL, DoD, ICBM, IED, KIA

Transportation & Travel Abbreviations

661 entries · ATC, DFW, DMV, ETA, LAX

Sports Abbreviations

452 entries · ERA, F1, FIFA, HR, KO

Arts & Entertainment Abbreviations

211 entries · DJ, PG-13, R&B, RPG, BPM

Religious Abbreviations

212 entries · AD, BC, KJV, NIV, Rev.

Organization & Company Abbreviations

454 entries · 501(c)(3), AA, AAA, AARP, ABC

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What is an abbreviation?

An abbreviation is a shortened form of a word or phrase, such as Dr. for doctor, Jan. for January or FBI for Federal Bureau of Investigation. The word comes from Late Latin abbreviare, “to shorten”, built on brevis, “short”. Abbreviations save space and time, but they only work when the reader knows what they stand for — the same three letters can be obvious to a nurse and baffling to a patient, or mean one thing in a contract and another in a text message.

Types of abbreviations

Type	How it is formed	Examples
Acronym	Initial letters pronounced as a word	NASA, NATO, laser, scuba
Initialism	Initial letters pronounced one by one	FBI, CPU, PRN
Contraction	First and last letters of a word, sometimes with letters from the middle	Dr. (Doctor), Mr. (Mister), Ltd. (Limited)
Truncation	The beginning of a word	Prof., Jan., Tues.
Latin abbreviation	A shortened Latin word or phrase	e.g., i.e., etc., BID
Symbol	A standardized unit, element or currency code	kg, Fe, USD
Numeronym	Letters combined with numbers	4WD, K-9, B2B

Abbreviation, acronym or initialism?

Every acronym and initialism is an abbreviation, but not every abbreviation is an acronym. Strictly speaking, an acronym is read as a word (NASA, NATO) while an initialism is spelled out letter by letter (FBI, CEO). In everyday English — and in many dictionaries — “acronym” is used for both. Some are said either way: ASAP can be pronounced as four letters or as “ay-sap”.

How to write abbreviations correctly

Periods. American English usually puts a period after contractions such as Mr., Mrs. and Dr.; British English generally leaves it out when the abbreviation ends with the last letter of the word (Mr, Mrs, Dr). Capital-letter initialisms are normally written without periods (FBI, CEO).
Plurals. Add a lowercase s without an apostrophe: CDs, PDFs, MDs. An apostrophe is only used where a plural would otherwise be confusing, as with single lowercase letters.
A or an. The article follows pronunciation, not spelling: an FBI agent (“eff”), a NASA engineer, an MRI scan, a URL (“you”).
First use. In formal writing, spell out the term the first time and give the abbreviation in parentheses — “transient ischemic attack (TIA)” — then use the short form.
Units. Unit symbols take no period and no plural s: 5 kg, 10 min, 3 ft. Letter case matters: mW is a milliwatt, MW a megawatt.
Medicine. Some abbreviations are banned in clinical records because they cause errors. The Joint Commission’s “Do Not Use” list includes U (unit), IU, QD, QOD and MS; the words are written out instead.